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This thesis consists of two studies on joint bandwidth and power allocation strategy for wireless communication networks. In the first study, joint bandwidth and power allocation strategy is proposed for wireless multi-user networks without relaying and with decode-and-forward relaying. It is shown that the formulated resource allocation problems are convex and, thus, can be solved efficiently. Admission control problem based on the joint bandwidth and power allocation strategy is further considered, and a greedy search algorithm is developed for solving it efficiently. In the second study, joint bandwidth and power allocation strategy is presented for maximizing the sum ergodic capacity of secondary users under fading channels in cognitive radio networks. Optimal bandwidth allocation is derived in closed-form for any given power allocation. Then the structures of optimal power allocations are derived. Using these structures, efficient algorithms are developed for finding the optimal power allocations. / Communications

It is conjectured that quantum computers are able to solve certain problems more quickly than any deterministic or probabilistic computer. For instance, Shor's algorithm is able to factor large integers in polynomial time on a quantum computer. A quantum computer exploits the rules of quantum mechanics to speed up computations. However, it is a formidable task to build a quantum computer, since the quantum mechanical systems storing the information unavoidably interact with their environment. Therefore, one has to mitigate the resulting noise and decoherence effects to avoid computational errors. In this dissertation, I study various aspects of quantum error control codes - the key component of fault-tolerant quantum information processing. I present the fundamental theory and necessary background of quantum codes and construct many families of quantum block and convolutional codes over finite fields, in addition to families of subsystem codes. This dissertation is organized into three parts: Quantum Block Codes. After introducing the theory of quantum block codes, I establish conditions when BCH codes are self-orthogonal (or dual-containing) with respect to Euclidean and Hermitian inner products. In particular, I derive two families of nonbinary quantum BCH codes using the stabilizer formalism. I study duadic codes and establish the existence of families of degenerate quantum codes, as well as families of quantum codes derived from projective geometries. Subsystem Codes. Subsystem codes form a new class of quantum codes in which the underlying classical codes do not need to be self-orthogonal. I give an introduction to subsystem codes and present several methods for subsystem code constructions. I derive families of subsystem codes from classical BCH and RS codes and establish a family of optimal MDS subsystem codes. I establish propagation rules of subsystem codes and construct tables of upper and lower bounds on subsystem code parameters. Quantum Convolutional Codes. Quantum convolutional codes are particularly well-suited for communication applications. I develop the theory of quantum convolutional codes and give families of quantum convolutional codes based on RS codes. Furthermore, I establish a bound on the code parameters of quantum convolutional codes - the generalized Singleton bound. I develop a general framework for deriving convolutional codes from block codes and use it to derive families of non-catastrophic quantum convolutional codes from BCH codes. The dissertation concludes with a discussion of some open problems.

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Communication applications have diverse network service requirements. For instance, <em>Voice over IP</em> (VoIP) demands short end-to-end delay, whereas <em>File Transfer Protocol</em> (FTP) benefits more from high throughput than short delay. However, the Internet delivers a uniform best-effort service. As a result, much research has been conducted to enhance the Internet to provide service differentiation. Most of the existing proposals require additional access-control mechanisms, such as admission control and pricing, which are complicated to implement and render these proposals not incrementally deployable. <em>Incentive-compatible Differentiated Scheduling</em> (ICDS) provides incentives for applications to choose a service class according to their burst characteristics without additional access-control mechanisms. <br /><br /> This thesis investigates the behaviour of ICDS with different types of traffic by analysis and extensive simulations. The results show some evidences that ICDS can achieve its design goal. In addition, this thesis revises the initial ICDS algorithm to provide fast convergence for TCP traffic.

Memoria para optar al título de Ingeniero Civil Eléctrico / El paradigma de comunicación Internet of Things (IoT), el cual plantea la posibilidad de interconectar objetos cotidianos y toda clase de dispositivos convencionales a Internet, está actualmente en pleno desarrollo. El gran número de nodos que se espera conectar a Internet exige a su vez la implementación a gran escala de Internet Protocol versión 6 (IPv6). IoT busca el desarrollo de nuevas aplicaciones y ha impulsado la creación de nuevas arquitecturas de red y nuevas clases de dispositivos. Las redes Low Power Wide Area Networks (LPWAN) han surgido recientemente como una evolución natural del concepto Wireless Sensor Networks (WSN), redes de sensores in- terconectadas. A la luz del IoT, las nuevas redes LPWAN abren un nuevo campo de desarrollo, principalmente enfocado en servicios de monitoreo y afines que se desarrollen en áreas am- plias y no requieran grandes tasas de transferencia. Los dispositivos LPWAN se caracterizan por ser de bajo consumo energético y de bajo costo, facilitando su despliegue masivo por largos períodos sin necesidad de recargar sus baterías. Long Range Wide Area Network (LoRaWAN) es una de las primeras y principales tec- nologías LPWAN, y presenta una gran flexibilidad que la hace ideal para redes de diseño propio. En América funciona en la banda industrial, científica y médica (ISM) alrededor de los 915 MHz. Sin embargo, también existen muchas otras tecnologías LPWAN con arquitec- turas y protocolos propietarios, lo que dificulta alcanzar la interoperabilidad que se desea en el entorno IoT. El grupo de trabajo para la implementación de IPv6 sobre redes LPWAN (lpwan WG) perteneciente al Internet Engineering Task Force (IETF) se encuentra actualmente desarrol- lando un mecanismo de compresión y fragmentación de paquetes IPv6 para redes LPWAN denominado Static Context Header Compression (SCHC). El esquema de compresión se en- cuentra terminado, pero aún no ha sido implementado ni evaluado de manera oficial. En este trabajo se presenta una plataforma experimental para la implementación y eval- uación del mecanismo SCHC sobre una red LoRaWAN consistente en un nodo terminal Mi- crochip y un Radio Gateway (RG) de Everynet. En su desarrollo se han integrado múltiples y diversas herramientas del campo de las Telecomunicaciones y las Tecnologías de Información y Comunicación (ICT). La plataforma creada logra una implementación básica pero exitosa del esquema de com- presión de SCHC. Por medio de ella se ha llevado a cabo una evaluación preliminar del funcionamiento de SCHC, analizando el nivel de compresión logrado por el mecanismo para tres contextos de comunicación característicos de una red LPWAN. Los resultados obtenidos son positivos.

Communication applications have diverse network service requirements. For instance, <em>Voice over IP</em> (VoIP) demands short end-to-end delay, whereas <em>File Transfer Protocol</em> (FTP) benefits more from high throughput than short delay. However, the Internet delivers a uniform best-effort service. As a result, much research has been conducted to enhance the Internet to provide service differentiation. Most of the existing proposals require additional access-control mechanisms, such as admission control and pricing, which are complicated to implement and render these proposals not incrementally deployable. <em>Incentive-compatible Differentiated Scheduling</em> (ICDS) provides incentives for applications to choose a service class according to their burst characteristics without additional access-control mechanisms. <br /><br /> This thesis investigates the behaviour of ICDS with different types of traffic by analysis and extensive simulations. The results show some evidences that ICDS can achieve its design goal. In addition, this thesis revises the initial ICDS algorithm to provide fast convergence for TCP traffic.

Two research topics in next-generation optical networks with wavelength-division multiplexing (WDM) technologies were investigated: (1) scalability of network management and control, and (2) resilience/reliability of networks upon faults and attacks. In scalable network management, the scalability of management information for inter-domain light-path assessment was studied. The light-path assessment was formulated as a decision problem based on decision theory and probabilistic graphical models. It was found that partial information available can provide the desired performance, i.e., a small percentage of erroneous decisions can be traded off to achieve a large saving in the amount of management information. In network resilience under malicious attacks, the resilience of all-optical networks under in-band crosstalk attacks was investigated with probabilistic graphical models. Graphical models provide an explicit view of the spatial dependencies in attack propagation, as well as computationally efficient approaches, e.g., sum-product algorithm, for studying network resilience. With the proposed cross-layer model of attack propagation, key factors that affect the resilience of the network from the physical layer and the network layer were identified. In addition, analytical results on network resilience were obtained for typical topologies including ring, star, and mesh-torus networks. In network performance upon failures, traffic-based network reliability was systematically studied. First a uniform deterministic traffic at the network layer was adopted to analyze the impacts of network topology, failure dependency, and failure protection on network reliability. Then a random network layer traffic model with Poisson arrivals was applied to further investigate the effect of network layer traffic distributions on network reliability. Finally, asymptotic results of network reliability metrics with respect to arrival rate were obtained for typical network topologies under heavy load regime. The main contributions of the thesis include: (1) fundamental understandings of scalable management and resilience of next-generation optical networks with WDM technologies; and (2) the innovative application of probabilistic graphical models, an emerging approach in machine learning, to the research of communication networks.

ITC/USA 2014 Conference Proceedings / The Fiftieth Annual International Telemetering Conference and Technical Exhibition / October 20-23, 2014 / Town and Country Resort & Convention Center, San Diego, CA / In this paper we consider the possibility of using a communications system that is operating between probes on the surface of an asteroid and an orbiting satellite to more accurately determine spatial positions. This is done by measuring the round trip communication delay between the orbiter and various surface probes to estimate distance. From these distance measurements, the position can be determined using trilateration - the same basic technique behind the earth-based GPS system. Within the framework of this scenario, the location of the probes or the orbiter can be determined depending on the scenario.